Scientists take a bird’s eye view to prevent bird-aircraft collisions

Knowing how a bird sees can help us design planes that are easier to spot.

The audio recordings are stark. “Birds,” the captain remarked. Thump. Thud. Then a shuddering sound was heard, followed by a decrease in engine noise as both of the engines’ fans started to slow. “Mayday mayday mayday...this is....Cactus fifteen-fourty-nine. Hit birds. We’ve lost thrust in both engines. We’re turning back towards LaGuardia.” Unable to safely make it back to the airport, the captain announced, “We’re gonna brace,” before dramatically ditching the plane on the Hudson River.

The emergency landing of US Airways Flight 1549 in 2009 gave increased media attention to bird-aircraft collisions, which poses a significant concern globally to both civil and military aviation. In addition to safety issues, bird strikes also pose a significant financial burden; worldwide, the cost to civil aviation alone exceeds $1.2 billion a year.

Because birds see so differently from humans, scientists are relying on their knowledge of bird visual systems to come up with possible solutions to reduce the risk of wildlife strikes to airplanes. New research by the US Department of Agriculture has found that using lights to make airplanes more visible to birds could help reduce the risk of bird strikes. The study, which examined how Canada geese responded to different radio-controlled model airplanes, is the first of its kind and was published last week in the British Ecological Society’s Journal of Applied Ecology.

Many bird species are adapting to living in urban environments, and quieter aircraft engines are more difficult for birds to detect and avoid. As a result, the threat of bird-aircraft collisions has grown. While success has been achieved in reducing bird strikes in the vicinity of the airport, little has been done to decrease risk beyond airport property. The risk for bird strikes at 500 feet above ground level has been increasing at a greater rate than those occurring below 500 feet, and over 20 percent of bird-aircraft collisions reported to the FAA occurred at altitudes over 2500 feet above ground level.

A team of researchers from the USDA, Indiana State University, and Purdue University used three radio-controlled model airplanes—one with the lights off, one with the lights on, and one painted to resemble a bird of prey—to test the response of Canada geese, a species responsible for a high rate of damaging bird strikes (including the one with US Airways Flight 1549). Although a predator might be more relevant to the geese’s normal experience, knowledge of the birds’ visual system suggested that light might capture their attention more readily.

The researchers found that geese responded more quickly to the model airplane with lights on, responding approximately 4 seconds earlier than the standard airplane with lights off. Using average flight speeds, the researchers estimate that geese responded to the aircraft with lights on from approximately 1,325 feet away, as opposed to 856 feet away with the lights off.

The study also found that geese responded the same way to both the standard airplane and the predator model. This finding is important, because to date, aviation authorities have not considered how birds respond to aircraft approach.

Since previous studies have found evidence that birds that collided with airplanes had tried to avoid them prior to impact, this earlier detection of planes could give birds the chance to effectively avoid collision. The authors conclude by noting that geese are very sensitive to violet and UV light, which could make the design of warning systems even more effective.

Allie Wilkinson
Allie is a freelance contributor to Ars Technica. She received a B.A. in Environmental Studies from Eckerd College and a Certificate in Conservation Biology from Columbia University's Earth Institute Center for Environmental Sustainability. Twitter@loveofscience

38 Reader Comments

Any sort of anti-bird collision technology will have to be closely guarded. Birds were an anti-aircraft defensive measure used against Nazi forces, initiated with technology no more complex than an umbrella.

Why not use a solution similar to the Boeing YAL-1? Surely anything designed to take down an ICBM could vaporize a bird. If a megawatt-class chemical oxygen iodine laser is deemed to dangerous at those lower altitudes were bird strikes are hazard, I'm sure they could dial down the power a bit.

I'm usually not one to comment on grammar and typos, but please have a copy editor re-read this. There are a number of glaring errors such as:

Quote:

The risk for bird strikes at above 500 feet above ground level has been increasing at a greater rate than those occurring below 500 feet, and over 20 percent of bird-aircraft collisions reported to the FAA occurred at altitudes over 2500 feet above ground level.

Might read better as:

Quote:

The risk for bird strikes at aboveover 500 feet above ground level has been increasing at a greater rate than those occurring below 500 feet, and over 20 percent of bird-aircraft collisions reported to the FAA occurred at altitudes over 2500 feet above ground level.

There is also the following:

Quote:

Since previous studies have found evidence that birds that collided with airplanes had tried to avoid them prior to impact, this earlier detection of planes could give birds the chance to effectively avoid a collision. The authors conclude by noting that geese are very sensitive to violet and UV light, which could make the design of warning systems even more effective

I always liked what they South Koreans did to fix the problem. They always sent out 5-7 very polite and funny young men on bicycles down to the end of the runways just before dawn, and they all proceeded to scare the shit out of everyone with their 12 gauge shotguns. 10 or so minutes going around and making noise drove them off for almost the entire day, and they rarely had to shoot any. But when they did, man that was some good eating!

Or maybe adapt the engines' intakes? On the Mig-29, "the main air inlet can be closed completely and alter using the auxiliary air inlet on the upper fuselage for takeoff, landing and low-altitude flying, preventing ingestion of ground debris" (http://en.wikipedia.org/wiki/Mig-29). The MIg-35 has mesh screens. Can something similar be designed for civil aviation?

Or maybe adapt the engines' intakes? On the Mig-29, "the main air inlet can be closed completely and alter using the auxiliary air inlet on the upper fuselage for takeoff, landing and low-altitude flying, preventing ingestion of ground debris" (http://en.wikipedia.org/wiki/Mig-29). The MIg-35 has mesh screens. Can something similar be designed for civil aviation?

That's great for avoiding ingestion, but Canada Geese also pose another problem: they're heavy enough that simple collisions can cause serious damage.

Since previous studies have found evidence that birds that collided with airplanes had tried to avoid them prior to impact, this earlier detection of planes could give birds the chance to effectively avoid collision. The authors conclude by noting that geese are very sensitive to violet and UV light, which could make the design of warning systems even more effective.

I certainly think a system that helps warn the animals would help, but unfortunately, birds' predator avoidance instincts don't always translate to effective airplane avoidance, and so, even if the birds have warning, they may not be so great at getting out of the planes's flight path in time. And what about a heavy traffic scenario, like you see every day above LAX or DFW ? The birds may avoid one plane, only to blunder into the path of another. This system would have to be combined with some intake protection schemes like described in some of the comments, plus systems to warn the humans involved in time for avoidance.Ideally, you'd want to keep birds out of the airport's approach and departure paths altogether.

There's really nothing new about using lights to warn birds away from airplanes. More than 30 years ago, the airline I was flying for told us to turn on all landing and taxi lights below 10,000 feet to make ourselves more visible. After that bird strikes were reduced, and for the DC-9, which has landing lights at the tips of the wings strikes were reduced much more than for, say, the A-320 which has its lights inboard.

If you look at the pictures of those Russian fighters, which are designed to operate from unimproved runways, you'll notice that the engines are in the fuselage, back far enough to fit an alternate intake setup, For a pod mounted engine ti would be much more difficult to implement. the airflow into a jet engine is critical and anything disrupting it while the engine is under full power has serious consequences. Those Russian fighters use the alternate intake only for the takeoff itself, so it wouldn't help them with low altitude birds either.

Why not use a solution similar to the Boeing YAL-1? Surely anything designed to take down an ICBM could vaporize a bird. If a megawatt-class chemical oxygen iodine laser is deemed to dangerous at those lower altitudes were bird strikes are hazard, I'm sure they could dial down the power a bit.

One of the things I learned from flying a light plane routinely around birds is that when confronted, birds tend to dive. So I've learned to climb!

Unfortunately most light plane owners keep their landing lights off during the day because the bulbs tend to burn out quickly with use. Anti-collision lights (e.g., strobes on the wingtips of newer aircraft) must always be on during flight, but aren't as visible from the front as landing lights.

Hmm...it seems that we have a solution: Turn on the lights and add some kind of screen to keep them out of the engine(s). Perfect? No. Effective? Yes.

Consider that most aircraft windshields are already designed to resist bird strikes, I bet that implementing the two items above would go a long way towards avoiding another AA1549, and reduce damage to aircraft as well.

I think an avoidance system for pilots isn't worth the effort. An aircraft on approach can't really swerve out of the way, particularly in high traffic environments.

Hmm...it seems that we have a solution: Turn on the lights and add some kind of screen to keep them out of the engine(s). Perfect? No. Effective? Yes.

Consider that most aircraft windshields are already designed to resist bird strikes, I bet that implementing the two items above would go a long way towards avoiding another AA1549, and reduce damage to aircraft as well.

I think an avoidance system for pilots isn't worth the effort. An aircraft on approach can't really swerve out of the way, particularly in high traffic environments.

You're suggesting that they implement a "screen" on a jet-plane engine? Jeeze, that's so obvious, I wonder why aerospace engineers didn't think of that.

There's really nothing new about using lights to warn birds away from airplanes.

Taking into account the specifics of birds' vision system is, though. So the results should only get better.

Seems kinda like one of those all-too-common cases where someone in one discipline just needed to ask someone in another, relevant discipline.

DDTad wrote:

Hmm...it seems that we have a solution: Turn on the lights and add some kind of screen to keep them out of the engine(s). Perfect? No. Effective? Yes.

Well, as long as you say a screen over a turbofan intake is effective, I guess that's all I need to hear. I won't worry about the effect on normal engine operation, nor worry about what happens when you now have goose carcass and screen tearing up the turbine rather than just a goose. Since you admitted it wasn't perfect, I know this is a realistic assessment.

Is there any reason why we cannot put a cow-catcher or other screen on the engines? Would it really hurt airflow that much?

Yes. Aircraft and high bypass turbofans in particular are very high tolerance pieces of equipment. Engines used in commercial aviation are designed to be light, powerful, efficient and safe. Changing the airflow characteristics of air entering or exiting the engine dramatically changes the efficiency and power of the engine. The precise characteristics of the airflow coming into the engine are taken into account, including the way the air moves over the various surfaces and enters the different parts of the engine.

I think that the most effective approach to this is going to be to take into account things like the fact that these large birds have eyesight that is far more sensitive in the UV range than in the lower ranges of light. Adding a series of UV lights to the leading edge of the wings spaced at regular intervals would certainly help the visibility profile of the aircraft take a serious step up for the birds.

The other thing to pay attention to in this article is that this isn't really discussing issues with strikes right at the ends of the runway. It is discussing strikes that occur between 500 and 2500 feet (or so), which will be a little ways out from that. Most airports have automatic noise making systems at the ends of the runways that are used to scare away birds on a regular basis (think blanks being fired at the end of the runway periodically).

What I am worried about though is how you warn a bird or flock of birds that is flying in the same direction as the aircraft? They won't be routinely looking behind themselves and because the sound of the aircraft will be slow to reach them, they might not have time to react before the aircraft overtakes them. In this case, the lighting wouldn't be of much help.

cdclndcWhy not use a solution similar to the Boeing YAL-1? Surely anything designed to take down an ICBM could vaporize a bird. If a megawatt-class chemical oxygen iodine laser is deemed to dangerous at those lower altitudes were bird strikes are hazard, I'm sure they could dial down the power a bit.

If they actually do use UV LEDs or mercury vapor "florescent" light sources, they'll likely need to rig something to interlock the lights to keep them off when on the ground. Don't need the ground crews getting blinded by the "goose lights".

If they actually do use UV LEDs or mercury vapor "florescent" light sources, they'll likely need to rig something to interlock the lights to keep them off when on the ground. Don't need the ground crews getting blinded by the "goose lights".

Simple, it's called a WOW switch (Weight On Wheels). Among other things it disarms the weapons systems on military aircraft when the aircraft is on the ground. I'm sure they would have them on civilian aircraft as well (who want's to accidentally retract landing gear on the ground) but my background is purely military in this area.

I always liked what they South Koreans did to fix the problem. They always sent out 5-7 very polite and funny young men on bicycles down to the end of the runways just before dawn, and they all proceeded to scare the shit out of everyone with their 12 gauge shotguns. 10 or so minutes going around and making noise drove them off for almost the entire day, and they rarely had to shoot any. But when they did, man that was some good eating!

Time to update the resume. I want this job. Heck, I'd do it for the cost of the supplies.

jiteo wrote:

Or maybe adapt the engines' intakes? On the Mig-29, "the main air inlet can be closed completely and alter using the auxiliary air inlet on the upper fuselage for takeoff, landing and low-altitude flying, preventing ingestion of ground debris" (http://en.wikipedia.org/wiki/Mig-29). The MIg-35 has mesh screens. Can something similar be designed for civil aviation?

I am not an avionics engineer (IANAAE?), but I'd imagine that the air flow demand from a fighter jet is not the same as what's needed by a commercial air liner. I'm fairly certain that the need to hang the engine from the wing (as opposed to inside the fuselage, as military fighters tend to do) has to do with the requirement that they need to pack some passengers in those big flying tubes, and that makes it further limiting as you don't want anything you don't absolutely have to have sitting on an airplane wing responsible for holding up several tons of fuselage.

Otherwise, I'd think that engineers would have played with this design already.

You're suggesting that they implement a "screen" on a jet-plane engine? Jeeze, that's so obvious, I wonder why aerospace engineers didn't think of that.

wyrmhole wrote:

Well, as long as you say a screen over a turbofan intake is effective, I guess that's all I need to hear. I won't worry about the effect on normal engine operation, nor worry about what happens when you now have goose carcass and screen tearing up the turbine rather than just a goose. Since you admitted it wasn't perfect, I know this is a realistic assessment.

OK then, can't put stuff in front of the engine. Got it. I guess we are left with fancy lights.

In my experience, Canada Geese are as dumb as the grass they eat. If you're hoping for any kind of predictable response from them, it better rely on triggering an instinctive reaction. If they need to "think" about it, you're doomed.

I like the "active defense" idea better. You don't need to blast the birds with enough energy to cook them, all you need is to singe their feathers enough to distract them so they lose altitude. The military has all kinds of neat toys that are designed to automatically lock onto fast-moving threats. You could add a turret to the aircraft with a high-power microwave generator, or maser, and an aiming mirror. Choose the frequency so that aircraft windows are 1/4-wave thick to keep from accidentally cooking any passengers.

Seriously, though, the most important thing is to make sure you don't make the situation worse. I'm reminded of "deer whistles" that you attach to the bumper of your car. The theory is that the deer will hear you coming and skedaddle into the bush. The anecdotal evidence is that the deer get startled and bolt across the road instead (for reasons only Bambi knows) -- resulting in more collisions, not less.